1. Field
The present invention relates to a rotational atherectomy device for removing or reducing stenotic lesions in blood vessels such as a human artery by rotating an abrasive element within the vessel to partially or completely ablate the unwanted material.
2. Description of the Related Art
Atherosclerosis, the clogging of arteries, is a leading cause of coronary heart disease. Blood flow through the peripheral arteries (e.g., carotid, femoral, renal etc.), is similarly affected by the development of atherosclerotic blockages. One conventional method of removing or reducing blockages in blood vessels is known as rotational atherectomy. A long guidewire is advanced into the diseased blood vessel and across the stenotic lesion. A hollow drive shaft formed from a torque transmitting coiled wire(s) is advanced over the guidewire. The distal end of the drive shaft terminates in a burr provided with an abrasive surface formed from diamond grit or diamond particles. The burr is positioned against the occlusion and the drive shaft rotated at extremely high speeds (e.g., 20,000-160,000 rpm).
As the burr rotates, the physician slowly advances it so that the abrasive surface of the burr scrapes against the occluding tissue and disintegrates it, reducing the occlusion and improving the blood flow through the vessel. Such a method and a device for performing the method are described in, for example, U.S. Pat. No. 4,990,134 to Auth. It is also known from U.S. Pat. No. 6,132,444 to Shturman (the instant inventor) et al., to provide a drive shaft which is also formed from a single layer of torque transmitting coiled wire or wires but different to the device described in U.S. Pat. No. 4,990,134 to Auth, mentioned above, by providing the drive shaft with an eccentric enlarged diameter section located proximally to and spaced away from the distal end of the drive shaft. This drive shaft is formed from a single layer of torque transmitting coiled wire(s). According to U.S. Pat. No. 6,132,444 to Shturman, abrasive particles are located around a maximum diameter of the eccentric segment of the drive shaft thereby forming an eccentric abrasive element positioned proximally to and spaced away from the distal end of the drive shaft.
A rotational atherectomy device with distal embolic protection capability is known from WO 2006/126076 to Shturman (the current inventor). In one preferred embodiment of this known Shturman application the distal end of the fluid impermeable drive shaft is advanced across the stenotic lesion to be treated and flushing fluid is pumped through the drive shaft in an antegrade direction to enter the vessel through at least one luminal opening located distally to the abrasive element. As a result of a continued flow of flushing fluid into the vessel in this way, a fluid pressure is generated in the vessel distal to the abrasive element which is sufficient to generate a retrograde flow of at least a portion of the flushing fluid around the abrasive element and the fluid impermeable drive shaft. This retrograde flowing flushing fluid entrains stenotic debris abraded by the rotating abrasive element and flows into a lumen of stationary drive shaft sheath thereby preventing distal migration of debris along the treated vessel. In the most preferred embodiment, abraded debris are not only being removed from the treated vessel but from the patient altogether.
According to the preferred embodiments of WO 2006/126076, it is also possible to provide inflatable support elements located distal and proximal to the abrasive element. The inflatable support elements may have centres of mass which are offset from the longitudinal axis of the drive shaft. Such support elements act as counterweights to the eccentric abrasive element, i.e. an abrasive element that has its centre of mass offset from the longitudinal axis of the drive shaft. Alternatively, the abrasive element and the support elements may have centres of mass which lie along the longitudinal axis of the drive shaft.
The rotational atherectomy device with fluid inflatable support elements has a smaller crossing profile than the rotational atherectomy device with solid support elements. The term ‘crossing profile’ refers to a maximum cross-sectional dimension of that portion of the device which has to be advanced across the stenotic lesion.
All embodiments of the device described in WO 2006/126076 have to be advanced along the treated vessel and across the stenotic lesion over the guidewire. The devices with fluid inflatable support elements known from WO 2006/126076 allow to reduce the crossing profile of the drive shaft of the device but they still have to be advanced across the stenotic lesion over the guidewire. The outer diameter of the drive shaft of any rotational atherectomy device with distal protection which is advanced over a guidewire may still be too large to cross very tight stenotic lesions. The present invention therefore seeks to provide a rotational atherectomy device with distal protection capability which does not require use of a guidewire for its advancement across the stenotic lesion to be treated. Such device may have a crossing diameter which is smaller than the crossing diameter of known rotational atherectomy devices with distal protection capability. The present invention also seeks to provide a rotational atherectomy device with distal protection capability that does not require occlusion of a distal end of the guidewire lumen prior to initiating flow of pressurized fluid through the guidewire lumen.
According to the present invention, there is provided a rotational atherectomy device for abrading a stenotic lesion from a vessel of a patient comprising a flexible drive shaft which extends towards a distal end of the device, a distal fluid inflatable support element located at a distal end of the drive shaft and an abrasive element mounted to the drive shaft proximal to and spaced away from the distal fluid inflatable support element, both the abrasive element and the distal fluid inflatable support element being rotatable together with the drive shaft, the drive shaft comprising a torque transmitting coil which defines a long lumen of the drive shaft, the distal fluid inflatable support element being formed from a fluid impermeable membrane that crosses a longitudinal axis common to the torque transmitting coil and the lumen of the drive shaft at the distal end of the device, thereby preventing pressurized fluid flowing along the lumen of the drive shaft from entering the vessel in the direction of said longitudinal axis so that fluid has to pass through the fluid inflatable support element, inflating said support element and exiting from the device through an outflow opening in the fluid inflatable support element in a direction different from the direction of the longitudinal axis of the coil and the lumen.
Preferably, this fluid impermeable membrane forms a wall of the distal fluid inflatable support element.
Preferably, the wall of the distal fluid inflatable support element extends around the torque transmitting coil of the drive shaft.
The wall of the distal fluid inflatable support element is preferably bonded to a surface of the torque transmitting coil proximal to the distal fluid inflatable support element.
In a preferred embodiment, the torque transmitting coil comprises at least one space which separates individual windings of the coil, said space allowing fluid communication between the lumen of the drive shaft and the distal fluid inflatable support element.
A preferred embodiment comprises an anchoring sleeve underlying the fluid impermeable membrane along at least a distal end portion of the drive shaft, the fluid impermeable membrane being attached to said anchoring sleeve proximal to the distal fluid inflatable support element.
Preferably, the torque transmitting coil has proximal and distal ends and an anchoring sleeve is disposed around at least a distal end portion of the torque transmitting coil.
Preferably, the torque transmitting coil has proximal and distal ends and the anchoring sleeve extends distally from the distal end of the coil such that the distal inflatable support element formed around the anchoring sleeve from the fluid impermeable membrane is spaced away from the distal end of the torque transmitting coil, the abrasive element being disposed around at least a portion of the circumference of the anchoring sleeve.
In an embodiment with one torque transmitting coil, the anchoring sleeve may extend proximally within and line the torque transmitting coil.
Preferably, the drive shaft comprises inner and outer torque transmitting coils, the anchoring sleeve being sandwiched between said inner and outer torque transmitting coils, the anchoring sleeve and the inner torque transmitting coil extending distally from a distal end of the outer torque transmitting coil, the abrasive clement being disposed around at least a portion of the circumference of the anchoring sleeve.
Preferably, the anchoring sleeve is closed at its distal end.
Preferably, the anchoring sleeve has an opening therein associated with the distal fluid inflatable support element to allow pressurised fluid to flow through said opening into the distal fluid inflatable support element from the lumen of the drive shaft.
Preferably, the distal end of the device and the closed distal end of the sleeve are spaced away from each other to form a soft atraumatic cushion between the distal end of the device and the closed distal end of the anchoring sleeve.
Preferably, the device comprises an elongate core element advanceable through the lumen of the drive shaft to stiffen the drive shaft and which assists in the advancement of the drive shaft along the vessel towards the treatment site.
The elongate core element preferably has a distal end configured for operational engagement with the distal end of the anchoring sleeve.
Preferably, the elongate core element is configured to be removed from the device after the distal end of the device has been advanced to the treatment site so that a detachable fluid supply tube can be attached to the device.
The elongate core element preferably includes a lumen for the passage of fluid therealong.
Preferably, the elongate core element has at least one opening located at or proximal to its distal end, said opening providing fluid communication between the lumen of the elongate core element and the lumen of the drive shaft.
The anchoring sleeve is preferably formed from a fluid impermeable membrane.
Preferably, the anchoring sleeve comprises at least one opening located proximal to the closed distal end of the sleeve, said opening providing fluid communication between the lumen of the drive shaft and the distal fluid inflatable support element.
Preferably, the distal fluid inflatable support element has, when inflated, a centre of mass which lies along the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft.
Preferably, a fluid inflatable space within the distal fluid inflatable support element extends uniformly around the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft to provide the distal support element with a centre of mass which lies along the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft when said distal support element is fluid inflated.
Preferably, there is a plurality of openings in the wall of the fluid inflatable distal support element, said openings being located around the circumference of the wall of the fluid inflatable distal support element such that, during rotation of the drive shaft, at least some of said openings face an inner surface of a treated vessel, so that flows of fluid through the openings form a layer of fluid between the outer wall of the fluid inflated distal support element and a wall of the treated vessel, said layer of fluid forming a fluid bearing between the outer wall of the rotating fluid inflated distal support element and the wall of the treated vessel.
Preferably, the rotational atherectomy device comprises a proximal fluid inflatable support element located proximal to and spaced away from the abrasive element, the proximal fluid inflatable support element having an outer wall.
Preferably, the outer wall of the proximal fluid inflatable support element is continuous and integral with the fluid impermeable membrane.
Preferably, the proximal fluid inflatable support element has, when inflated, a centre of mass which lies along the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft.
Preferably, a fluid inflatable space within the proximal fluid inflatable support element extends uniformly around a longitudinal axis of the torque transmitting coil and the lumen of the drive shaft to provide the proximal support element with a centre of mass which lies along the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft when said proximal support element is fluid inflated.
Preferably, there is a plurality of openings in the wall of the fluid inflatable proximal support element, said openings being located around the circumference of the wall of the fluid inflatable proximal support element such that, during rotation of the drive shaft, at least some of said openings face an inner surface of a treated vessel, so that flows of fluid through the openings form a layer of fluid between the outer wall of the fluid inflated proximal support element and a wall of the treated vessel, said layer of fluid forming a fluid bearing between the outer wall of the rotating fluid inflated proximal support element and the wall of the treated vessel.
Preferably, the abrasive element has a centre of mass which lies on the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft.
In a modified embodiment, the abrasive element may have a centre of mass which is offset in a radial direction from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft.
In an alternative embodiment of the invention, the centre of mass of the abrasive element is always offset in a radial direction from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft.
In the alternative embodiment, the distal fluid inflatable support element has, when inflated, a centre of mass which is offset in a radial direction from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft.
Preferably in the alternative embodiment, the centre of mass of the distal fluid inflatable support element and the centre of mass of the abrasive element are offset from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft in opposite directions.
In the alternative embodiment, preferably, the wall of the distal fluid inflatable support element is bonded to a segment of a circumference of the torque transmitting coil, a middle point of said segment being spaced from the longitudinal axis of the coil and the lumen of the drive shaft in the same direction as the centre of mass of the abrasive element.
In the alternative embodiment, preferably, the wall of the distal fluid inflatable support element defines a fluid inflatable space that extends only partially around a circumference of the torque transmitting coil so that, when the distal inflatable support element is fluid inflated, its centre of mass is offset from a longitudinal axis of the torque transmitting coil and the lumen of the drive shaft in one direction, the distal fluid inflated support element acting, during rotation of the drive shaft, as a counterweight to the abrasive element which has its centre of mass offset from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft in the opposite direction.
In the alternative embodiment, the abrasive element preferably has a centre of mass which is offset in a radial direction from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft, the wall of the distal fluid inflatable support element defining a fluid inflatable space that extends only partially around a circumference of the anchoring sleeve so that, when the distal inflatable support element is fluid inflated, its centre of mass is offset from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft in a direction opposite to the direction in which the centre of mass of the abrasive element is offset from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft, the distal fluid inflated support element acting, during rotation of the drive shaft, as a counterweight to the abrasive element.
Preferably, the alternative embodiment comprises a proximal fluid inflatable support element located proximal to and spaced away from the abrasive element, the proximal fluid inflatable support element having an outer wall which is bonded to a segment of the circumference of the torque transmitting coil, a middle point of said segment being spaced from the from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft in the same direction as the centre of mass of the abrasive element.
Preferably, the rotational atherectomy device of the alterative embodiment comprises a proximal fluid inflatable support element located proximal to and spaced away from the abrasive element, the proximal fluid inflatable support element having an outer wall which defines a fluid inflatable space that extends only partially around a circumference of the anchoring sleeve so that, when the proximal inflatable support element is fluid inflated, its centre of mass is offset from a longitudinal axis of the torque transmitting coil and the lumen of the drive shaft in a direction opposite to the direction in which the centre of mass of the abrasive element is offset from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft, the proximal fluid inflated support element acting, during rotation of the drive shaft, as a counterweight to the abrasive element.
Preferably, in the alternative embodiment, the abrasive element has a centre of mass which is offset in a radial direction from the longitudinal axis of the torque transmitting coil and lumen of the drive shaft, the walls of the distal and proximal fluid inflatable support elements defining fluid inflatable spaces that extend only partially around a circumference of the torque transmitting coil so that, when the inflatable support elements are fluid inflated, their centres of mass are offset from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft a direction opposite to the direction in which the centre of mass of the abrasive element is offset from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft, the fluid inflated support elements acting, during rotation of the drive shaft, as a counterweights to the abrasive element.
Preferably, in the alternative embodiment, the wall of the distal fluid inflatable support element has an outflow opening located such that said outflow opening, during rotation of the drive shaft, faces an inner surface of a treated vessel so that fluid flowing through the outflow opening forms a layer of fluid between the outer wall of the rotating fluid inflated distal support element and a wall of the treated vessel, said layer of fluid forming a fluid bearing between the outer wall of the rotating fluid inflated distal support element and the wall of the treated vessel.
Preferably, in the alternative embodiment, at least a few openings in the outer wall of a rotating fluid inflated distal support element are located around a circumference of the wall of the inflated distal support element such that at any time during rotation of the drive shaft at least one of said few openings is facing an inner surface of a treated vessel, so that a flow of fluid through the opening forms a layer of fluid between the wall of the rotating fluid inflated distal support element and a wall of the treated vessel, said layer of fluid forming a fluid bearing between the wall of the rotating fluid inflated support element and the wall of the treated vessel.
Preferably, in the alternative embodiment, at least one opening in the wall of a rotating fluid inflated proximal support element is located such that at any time during rotation of the drive shaft said opening is facing an inner surface of a treated vessel, so that a flow of fluid through the opening forms a layer of fluid between the wall of the rotating fluid inflated proximal support element and a wall of the treated vessel, said layer of fluid forming a fluid bearing between the wall of the rotating fluid inflated proximal support element and the wall of the treated vessel.
Preferably, in the alternative embodiment, at least a few openings in the outer wall of a rotating fluid inflated proximal support element are located around circumference of the wall of the inflated distal support element such that at any time during rotation of the drive shaft at least one of said few openings is facing an inner surface of a treated vessel, so that a flow of fluid through the opening forms a layer of fluid between the wall of the rotating fluid inflated proximal support element and a wall of the treated vessel, said layer of fluid forming a fluid beating between the wall of the rotating fluid inflated support element and the wall of the treated vessel.
Preferably, the walls of both inflatable support elements are made from a continuous stretchable membrane, said fluid impermeable stretchable membrane being sandwiched between the torque transmitting coil and at least one non-stretchable sleeve, the non-stretchable sleeve being disposed around the stretchable membrane between the fluid inflatable support elements. Preferably, the non-stretchable sleeve is formed in two sections, each section being disposed on either side of the abrasive element. Preferably, a second long, non-stretchable sleeve overlaps the stretchable membrane for a short distance proximal to the proximal fluid inflatable support element and extends in a proximal direction around the torque transmitting coil towards the proximal end of the drive shaft. Preferably, the non-stretchable sleeve is fluid impermeable.
Preferably, in the above-described alternative embodiment, the abrasive element has a centre of mass which is spaced away from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft, and an anchoring sleeve is disposed around the torque transmitting coil at least along a length of the drive shaft occupied by fluid inflatable support elements, said anchoring sleeve being disposed over the coil under the fluid impermeable membrane which forms fluid inflatable support elements, the fluid impermeable membrane along a length of the fluid inflatable support elements being bonded to the anchoring sleeve only along one side of a circumference of the drive shaft, thereby preventing the fluid inflatable support elements from expanding uniformly around an entire circumference of the anchoring sleeve when fluid inflated so as to form fluid inflated counterweights with centres of mass spaced radially away from a longitudinal axis of the torque transmitting coil and the lumen of the drive shaft in a direction opposite to the direction in which the centre of mass of the abrasive element is spaced away from the longitudinal axis of the torque transmitting coil and the lumen of the drive shaft.
Preferably, the lumen of the drive shaft has proximal and distal portions, the proximal portion of the lumen having a larger cross-sectional area relative to the cross-sectional area of the distal portion of the lumen so that per unit of length hydraulic resistance to fluid flow of the proximal portion of the lumen is less than the hydraulic resistance to fluid flow of the distal portion of the lumen.
Preferably, all the pressurised fluid which flows through the lumen of the drive shaft exits from the device into the vessel through opening(s) in the wall(s) of the fluid inflatable support elements.
Preferably, the abrasive element is spaced away from the distal end of the torque transmitting coil.
Preferably, in the rotational aherectoomy device which has inner and outer torque transmitting coils, the abrasive element is spaced away from the distal end of the outer torque transmitting coil.
According to the present invention, there is provided a rotational atherectomy device for abrading a stenotic lesion from a vessel of a patient comprising a rotatable, flexible drive shaft, a distal fluid inflatable support element located at a distal end of the device and an abrasive element mounted to the drive shaft proximal to and spaced away from the distal fluid inflatable support element, both the abrasive element and the distal fluid inflatable support element being rotatable together with the drive shaft, the drive shaft comprising a torque transmitting coil which defines a long lumen of the drive shaft, the distal fluid inflatable support element being formed from a fluid impermeable membrane that crosses a longitudinal axis common to the torque transmitting coil and the lumen of the drive shaft at the distal end of the device, thereby preventing pressurized fluid flowing along the lumen of the drive shaft from entering the vessel in the direction of said longitudinal axis so that fluid has to pass through the fluid inflatable support element, inflating said support element and exiting from the device through an outflow opening in the fluid inflatable support element in a direction different from the direction of the longitudinal axis of the coil and the lumen.
In one preferred embodiment, the abrasive element has a centre of mass which is offset in a radial direction from the longitudinal axis of the coil and the lumen of the drive shaft. In another preferred embodiment, the abrasive element has a centre of mass which lies on the longitudinal axis of the coil and the lumen of the drive shaft.
The fluid impermeable membrane preferably extends around and is bonded to a surface of the torque transmitting coil proximal to the distal fluid inflatable support element.
The wall of the distal fluid inflatable support element preferably extends around the torque transmitting coil of the drive shaft.
In one preferred embodiment, the wall of the distal fluid inflatable support element is bonded to a segment of the circumference of the torque transmitting coil, a middle point of said segment being spaced from the longitudinal axis of the coil and the lumen of the drive shaft in the same direction as the centre of mass of the abrasive element.
The torque transmitting coil preferably comprises at least one space which separates individual windings of the coil, said space allowing fluid communication between the lumen of the drive shaft and the distal fluid inflatable support element.
One preferred embodiment comprises an anchoring sleeve underlying the fluid impermeable membrane along at least a distal end portion of the drive shaft, the fluid impermeable membrane being attached to said anchoring sleeve proximal to the distal fluid inflatable support element.
In one preferred embodiment, the torque transmitting coil has proximal and distal ends and the anchoring sleeve is disposed around at least a distal end portion of the torque transmitting coil.
Preferably, the torque transmitting coil has proximal and distal ends and the anchoring sleeve extends distally from the distal end of the coil such that the distal fluid inflatable support element formed around the anchoring sleeve from the fluid impermeable membrane is spaced away from the distal end of the torque transmitting coil and disposed (located) around at least a portion of the circumference of the anchoring sleeve.
The anchoring sleeve may extend proximally within and line the torque transmitting coil.
In a preferred embodiment, the drive shaft comprises inner and outer torque transmitting coils, the anchoring sleeve being sandwiched between said inner and outer torque transmitting coils, the anchoring sleeve and the inner torque transmitting coil extending distally from the distal end of the outer torque transmitting coil, the abrasive element being located around at least a portion of the circumference of the anchoring sleeve and being spaced away from the distal end of the outer torque transmitting coil.
In one embodiment, the anchoring sleeve may be closed at its distal end. In one embodiment, the anchoring sleeve may have an opening therein associated with the distal fluid inflatable support element to allow pressurised fluid to flow through said opening into the distal fluid inflatable support element from the lumen of the drive shaft.
The distal end of the device may be closed by the fluid impermeable membrane and spaced in a longitudinal direction from the closed distal end of the anchoring sleeve to form a soft atraumatic cushion at the distal end of the device.
One preferred embodiment of the invention may comprise an elongate core element advanceable through the lumen of the drive shaft to stiffen the drive shaft and thereby assist in the advancement of the drive shaft along the vessel towards the treatment site.
The elongate core element may have a distal end configured for operational engagement with the distal end of the anchoring sleeve.
The elongate core element may be configured to be removed from the device after the distal end of the device has been advanced to the treatment site so that a detachable fluid supply tube can be attached to the device.
In one preferred embodiment, the elongate core element includes a lumen for the passage of fluid therealong, the elongate core element preferably having at least one opening located at or proximal to its distal end, said opening providing fluid communication between the lumen of the elongate core element and the lumen of the drive shaft.
The elongate core element may have a coil at its distal end, and the elongate core element may be a coil.
Preferably, the anchoring sleeve is formed from a fluid impermeable membrane.
The anchoring sleeve may comprise at least one opening located proximal to the closed distal end of the sleeve, said opening providing fluid communication between the lumen of the drive shaft and the distal fluid inflatable support element.
In a preferred embodiment, the device comprises a proximal fluid inflatable support element located proximal to and spaced away from the abrasive element, the proximal fluid inflatable support element having an outer wall.
In one preferred embodiment, the outer wall of the proximal fluid inflatable support element is continuous and integral with the fluid impermeable membrane.
The wall of the proximal fluid inflatable support element may be bonded to a segment of the circumference of the torque transmitting coil, a middle point of said segment being spaced from the longitudinal axis of the drive shaft in the same direction as the centre of mass of the abrasive element.
The torque transmitting coil may comprise at least one space which separates individual windings of the coil, said space allowing fluid communication between the lumen of the drive shaft and the proximal fluid inflatable support element.